(News) Nanotyrannus specimen "Bloody Mary" was an adult, and Nanotyrannus was related to Dryptosaurus (Zanno and Napoli, 2025)!

Nanotyrannus pack attacking a juvenile Tyrannosaurus by Anthony Hutchings (2025) from Egan (2025):

It's over! Nanotyrannus is a valid species, and is a basal tyrannosauroid! Zanno and Napoli (2025) have uploaded a paper, albeit it's an "unedited version" of the paper that is still being edited. The paper is also behind a paywall (boo!), but the abstract is available on Nature. The "Bloody Mary" specimen of Nanotyrannus, cataloged as NCSM 40000, was "near somatically mature" in terms of age. It also shares characteristics to the holotype of Nanotyrannus lancensis, CMNH 7541, cementing it in the taxon. However, the two scholars throw a curve-ball in their abstract: there are TWO Nanotyrannus species: N. lancensis and N. lethaeus. We officially have two genera of tyrannosaurs coexisting at the end of the Cretaceous in North America (Abstract):

My boy "Luke" sent me a picture of the phylogenetic charts that have been posted on Twitter-X:

My friend on Discord downloaded the paper. Here's the full chart (Figure 6 [p. 38]): 

Description (pp. 18-19):

Aside from Moros flip-flopping between Eutyrannosauria (top) and Pantyrannosauria (bottom), you can see Nanotyrannus and Dryptosaurus being put in the eutyrannosaurian clade. This confirms the results of Longrich and Saitta (2024) and Paul (2025b). Interestingly, the Zanno and Napoli placed Dryptosaurus and Appalachiosaurus in the new Nanotyrannidae clade, named after Nanotyrannus. Since Dryptosaurus was named before Nanotyrannus, I would've gone with Dryptosauridae. Also, I still think calling the taxa Nanotyrannus/Dryptosaurus lancensis and Nanotyrannus/Dryptosaurus lethaeus are still valid taxonomic names. However, I don't care! I'm still elated by the news! More phylogenetic charts are listed in the Extended Data section.

Phylogenetic charts 2 (Zanno and Napoli, 2025, Extended Data Figure 9 [p. 47]):

Description (p. 32):

Phylogenetic charts 3 (Zanno and Napoli, 2025, Extended Data Figure 10 [p. 48]):

Description (p. 32):

I want to make a quick note about "Stygiovenator." Paul (2025b) put NCSM 40000 in "Stygiovenator," but now this specimen is in Nanotyrannus lancensis (Zanno and Napoli, 2025, Discussion: A Skeletally Mature Nanotyrannus, para. 1 [p. 6]; Figures 1 and 2 [pp. 17, and 33-34]). BMRP 2002.4.1 ("Jane") is in N. lethaeus (Discussion: A Skeletally Mature Nanotyrannus, para. 1 [p. 6]; Figure 1 [pp. 17 and 33]). Interestingly, BMRP 2006.4.4 ("Petey") is called Nanotyrannus sp. (Discussion: A Skeletally Mature Nanotyrannus, para. 1 [p. 6]). I'm putting "Stygiovenator" as a synonym of Nanotyrannus lancensis.

NCSM 40000 with two EFS (External Fundamental Systems) in its femur and tibia (Figure 3 [p. 35]):

Description (p. 18):

I found a picture showing the arm of NCSM 40000 compared to Tyrannosaurus' (Egan, 2025):

I think the Tyrannosaurus arm belongs to either the specimens MOR 980, or FMNH PR 2081. This is Figure 5 in the paper (p. 37):

Description (p. 18):

The Tyrannosaurus forelimb belongs to FMNH PR 2081.

I have been through a lot since I posted my own abstract back in 2022. Now, we have undeniable proof that Nanotyrannus was a distinct taxon and was related to Dryptosaurus. We also have two adult specimens now (CMNH 7541 and NCSM 40000). Longrich and Saitta (2024), and Paul (2025b), were correct as well. They also placed Nanotyrannus as a basal tyrannosauroid (eutyrannosaurian). Paul (2025b) also agreed with me that Nanotyrannus was closely related to Dryptosaurus.

I have to personally thank my friend "Luke" from Instagram. For years now, he gave support to my hypothesis on Nanotyrannus. He has proven to be a good friend. I did feel like giving up, especially after what happened in 2023, but he helped to keep me motivated. Now, the fruits of that labor have paid off positively. I'm forever indebted to you, my friend. 

Links:

Zanno and Napoli (2025) (Abstract):
https://www.nature.com/articles/s41586-025-09801-6

Egan (2025):
https://phys.org/news/2025-10-nanotyrannus-dueling-dinosaurs-fossil-rewrites.html